Hand held boiling point test devices are well known and they consist usually of a ‘probe’ housing containing heating elements and temperature monitoring devices. These known devices heat the test fluid within the probe housing using the heating elements and monitor the temperature rise within the fluid, usually taking the maximum temperature attained as the boiling point. Some of these testers use substantially restricted openings (approx. 1 mm) for fluid flow to and from the probe housings to create oscillations at boiling point so as to discern the boiling point. Other such devices use an air lock within the probe housing to isolate the test fluid from the reservoir during the time the test fluid is heated to its boiling point.
The main commercial use of these test devices is the testing of the boiling point of the Hygroscopic Brake Fluid used, for example, in motor vehicle brake systems. The known boiling point test devices are, however, not quick enough, not suitable for receiving replaceable or rechargeable batteries, or capable of on-vehicle testing of fluids in shallow brake fluid reservoirs.